The technical field of this invention is a vehicle occupant protection system and particularly an occupant detection system for a vehicle seat.
Vehicle occupant protection systems are beginning to include occupant detection and characterization systems for helping to decided whether or how to deploy an airbag in a crash event. At least one such system provides an occupant characteristic sensor in a vehicle seat member to determine the weight of a seat occupant. The determination is made by a programmed computer provided in an occupant detection system module, the computer having an input connection from a seat characteristic sensor such as a fluid pressure sensor connected to a fluid filled bladder on the seat pan under the bottom seat cushion member. The output signal from the sensor is compared with calibrated threshold values to characterize a detected seat occupant.
The calibrated threshold values are initially determined in calibration tests of the occupant detection system, which includes the seat cushion member, bladder, sensor and occupant detection system module, and are typically stored in rewritable, non-volatile memory such as EEPROM in the occupant detection system module to allow updating during vehicle operation, service or recalibration. If service of the system requires part replacement, there are typically two alternative replacement modes: (1) replacement of the entire system, including seat member, bladder, sensor and module, or (2) replacement of the module alone. The latter mode of replacement will result in loss of the calibrated threshold values with the discarded module unless additional steps are taken, such as specifically copying these values to the new module or recalibrating the system. But a defect in the replaced module may prevent access to the stored calibrated threshold values; and recalibration requires special equipment not generally available outside manufacturing facilities.
This invention is a method and apparatus for preserving seat calibration data such as the calibrated threshold values in an occupant detection system in an automatic manner, regardless of which replacement mode is performed. The invention provides dedicated memory locations for vehicle identification data and seat calibration data in a first rewritable, non-volatile memory within an occupant detection system module and a second rewritable, non-volatile memory external to the occupant detection system. The second rewritable, non-volatile memory may, in a preferred embodiment, be located within an airbag control module that is separately replaceable in the vehicle with respect to the occupant detection system.
In one aspect of the invention, vehicle identification data is obtained from the vehicle. If the vehicle identification data obtained from the vehicle matches vehicle identification data stored in the first rewritable, non-volatile memory, seat calibration data stored in the first rewritable, non-volatile memory is copied to the second rewritable, non-volatile memory.
In another aspect of the invention, vehicle identification data is obtained from the vehicle. If (a) there is vehicle identification data in the first rewritable, non-volatile memory and (b) the vehicle identification data obtained from the vehicle does not match the vehicle identification data stored in the first rewritable, non-volatile memory and (c) the vehicle identification data obtained from the vehicle matches vehicle identification data stored in the second rewritable, non-volatile memory, then seat calibration data stored in the second rewritable, non-volatile memory and one of the vehicle identification data obtained from the vehicle and the vehicle identification data stored in the second rewritable, non-volatile memory is copied to the first rewritable, non-volatile memory.
In another aspect of the invention, vehicle identification data is obtained from the vehicle. If (a) there is no vehicle identification data stored in the first rewritable, non-volatile memory, and (b) there is seat calibration data stored in the first rewritable, non-volatile memory, then (a) the vehicle identification data obtained from the vehicle is copied to the first rewritable, non-volatile memory and to the second rewritable, non-volatile memory and (b) the seat calibration data in the first rewritable, non-volatile memory is copied to the second rewritable, non-volatile memory.
In yet another aspect of the invention, vehicle identification data is obtained from the vehicle. If (a) there is no vehicle identification data stored in the first rewritable, non-volatile memory and (b) there is no seat calibration data stored in the first rewritable, non-volatile memory and (c) the vehicle identification data obtained from the vehicle matches the vehicle identification data stored in the second rewritable, non-volatile memory, then seat calibration data stored in the second rewritable, non-volatile memory and one of the vehicle identification data obtained from the vehicle and the vehicle identification data stored in the second rewritable, non-volatile memory is copied to the first rewritable, non-volatile memory.
In a preferred embodiment of the invention, the second rewritable, non-volatile memory may be located in an airbag control module separately packaged and replaceable with respect to the occupant detection system.